Jose Fernandez and Adam Conley, the team's first- and second-round picks in 2011, are making their debuts with the Hammerheads. They are ranked No. 3 and No. 7, respectively, among Marlins prospects by MLB.com.
Fernandez, 19, will be pitching for the first time at Jupiter on Thursday night at Roger Dean Stadium.
On Wednesday night, the left-handed Conley got the starting nod in Game 2 of a doubleheader at Lakeland.
Fernandez, a hard-throwing right-hander, was 7-0 with a 1.59 ERA in 14 starts at Class A Greensboro. He has thrown 79 innings, striking out 99 with 18 walks. Batters are hitting just .189 off him.
Conley, who turned 22 this past Sunday, was 7-3 with a 2.78 ERA in 14 starts, striking out 84 in 74 1/3 innings.
Marlins vice president of player development Marty Scott says both accomplished at the lower Class A level. Now, they're ready for higher competition.
"You want to continue the development without rushing them," Scott said. "You want to make sure they earn each promotion and not just push them because of where they were drafted or who they are."
As an organization, the Marlins are mindful of developing their top prospects without having to rush them. The aim is to give them as much seasoning as possible before they arrive at the big leagues.
"It's not always the development of those guys, but the development of the organization, and building some depth," Scott said. "You do that by not rushing them, and letting them develop a step at a time. Sooner or later, that all filters to the top.
"Hopefully, the days are over of rushing people just out of necessity to get to the big leagues because they have potential. You hope the process is slowed down a little bit to give them the experience they need, so when they are ready to come to the big leagues, they come and they stay. It's not a revolving door back to Triple-A and back to the big leagues all the time."